The invention relates to left ventricular intracardiac pacing leads.
The invention is in the general context of “active implantable medical devices” as defined by Directive 90/385/EEC of 20 Jun. 1990 the Council of the European Communities, including implants to continuously monitor heart rhythm and deliver as necessary the electrical stimulation, resynchronization or defibrillation pulses to the heart.
Intracardiac “stimulation” leads will mainly be referenced herein, that is to say, leads for the delivery of low-energy pulses used for bradycardia or resynchronization therapies. But the invention also applies to cardioversion/defibrillation intracardiac leads intended to deliver an electric shock of high energy to the heart to try to terminate a tachyarrhythmia. Unless otherwise indicated, the generic terms “stimulation lead (or electrode)” or “pacing/defibrillation lead” may designate any kind of lead used for these purposes, regardless of the type and level of electrical energy delivered.
For right ventricular stimulation, implanting an endocardial lead by the right peripheral venous network is sufficient. However, for left ventricular stimulation, the situation is more complex.
A wide variety of solutions have been proposed for this purpose: lead inserted into the coronary network via the right atrium and the ostium of the coronary sinus, catheter inserted in the right ventricle and positioned against the wall of the interventricular septum, or piercing of the septum then introduction of a lead through the septum until the latter comes into contact with an inner wall of the left ventricle.
Another technique, more difficult to implement and being much more invasive, is to implant epicardial electrodes on the outer myocardium wall, in one or more suitable sites arranged facing the cavity of the left ventricle. The implantation of such a lead is however a very heavy operation, usually requiring general anesthesia and the use of highly invasive surgical techniques. For this reason, this solution is often considered a last resort in case of failure of implantation via the coronary sinus. In addition, the electrical performance is often poor, and it is very difficult to change the implantation site initially chosen and, if necessary, to explant the lead later.
U.S. 2008/0294229 A1 discloses a pacing lead in particular for the left ventricular stimulation by implantation in the thickness of the septal wall, or in the thickness of the left ventricular free wall, below the surface and along this region of this wall between the apex and the atrial region.
U.S. 2005/0080470 A1 describes a specific transthoracic implantation technique of a detection/stimulation lead. However, this technique is particularly invasive, because of the high caliber of the instruments used to cross the chest.